The present invention relates to a process for polymerizing or copolymerizing .alpha.-olefins in high activity and with high stereospecificity by using a novel catalyst.
Catalysts comprising titanium halides and organoaluminum compounds have heretofore been known as high stereospecific polymerization catalysts for .alpha.-olefins. However, although polymerizations using such known catalysts afford highly stereospecific polymers, it is necessary to remove the catalyst remaining in the resultant polymer because of a low catalytic activity.
Recently, various proposals have been made for improving the catalytic activity. According to those proposals, a high catalytic activity is attained when using a catalyst component which comprises an inorganic solid carrier such as, for example, MgCl.sub.2 and titanium tetrachloride supported thereon.
In the preparation of polyolefins, however, it is preferable that the catalytic activity be as high as possible. From this standpoint, a catalyst of even higher activity has been desired. It is also important that the proportion of atactic portion in the resultant polymer be as small as possible.